Deborah Vollmer wants to make one thing very clear. Under no circumstances can you park on the driveway. This is not a drill. This is not a joke. Please park on the street.

This isn’t just a driveway, Vollmer explained, stepping across it on a soggy Thursday morning. It is the fault line dividing two titanic forces, a battlefield between past and present, between the haves and the have-nots, between environmental conservation and environmentaldegradation.

Put another way, the driveway separates her million-dollar house from her neighbor’s million-dollar house.

Suddenly, a figure materialized at the window in the neighbor’s house. It was Vollmer’s next-door neighbor and nemesis — an elegantly dressed, blond-haired woman named Linda Schwartz, who at this precise moment looked very unhappy. Seconds later, a garage door screeched open and Schwartz backed her ­Mercedes-Benz onto the driveway.

Vollmer, eyes widening in alarm, darted out of sight. “I got to get out of here!” she yelled as she vamoosed. “There’s a no-contact order against me!”

Deborah Vollmer, 67, is photographed at her home on June 5, 2015, in Chevy Chase, Md. (Ricky Carioti/The Washington Post)

Schwartz rolled the Mercedes to a stop and lowered her car window. She uttered a few words in disgust and then drove off.

Thus passed another tense moment in what local officials say has become the town of Chevy Chase’s lengthiest, costliest, and most litigious neighborhood spat in recent memory. What began as a contested building permit six years ago has spiraled into a clash of wills, spawning five lawsuits, two misdemeanor convictions, arrests, anger-management classes, and a court order that Vollmer steer clear of the Schwartzes — or risk spending 18 months in the slammer.

“It is so sad that this has happened,” said Arthur Schwartz. “She is independently wealthy, has not had to work and has little else to do but continue to sue us and her own town, without regard to the law or what any court has told her.”

This squabble, silly though it may be, nonetheless explains big things around town. The town of Chevy Chase has undergone significant changes in aesthetic over the past 15 years as it has transitioned from a wealthy enclave of 1,000 homes into an evenwealthier enclave of 1,000 homes. In the “mansionization” of Chevy Chase, contractors have demolished dozens of smaller homes — called teardowns — to make way for palatial structures.

Vollmer, a retired lawyer who spent much of her career defending people who couldn’t afford lawyers, hates mansions. The closer they look to how they did when she was a child, the better. And so it was that she banded together with a group of residents around a decade ago to successfully lobby the Chevy Chase Town Council to pass a moratorium on demolition and new constructions.

“Change is inevitable,” Chevy Chase Town Manager Todd Hoffman sighed. “And it’s how you manage it. The council has tried to manage it in such a way as to obviously not stop redevelopment but to control its ill effects.”

Vollmer watched this archetypal struggle between community values and individual property rights seesaw back and forth until one day, in 2008, it landed on her front doorstep. That year, she got two new neighbors, Linda and Arthur Schwartz. According to Vollmer, whose assertions are up for debate, the couple wanted to “mansionize” the plot next door.

In response, she declared all-out war.

First, in 2009, she sued the town of Chevy Chase in an attempt to block its approval of the Schwartzes’ building permit — but that failed. Then she appealed — and was denied. “I would say Chevy Chase has spent upwards of $50,000 because of Deborah,” Hoffman said. “Not just in legal bills, but in all the staff costs in answering her letters and telephone calls.”

Vollmer next filed a similar lawsuit against Montgomery County and lost again. Soon afterward, she watched in horror as the Schwartzes erected a handsome, stone-encrusted house at 7200 44th St. The house, which she excoriated for its size, offers evidence of the neighbors’ clashing lifestyles.

Vollmer drives a Prius. The Schwartzes have a Mercedes. Vollmer prizes rough-hewn back yards with lots of vegetation. The Schwartzes appreciate a more manicured aesthetic. “Some people may question my motives,” Vollmer said. “But what’s happening in this town, these developers, tearing down old homes. I’m standing up for my rights. . . . And then this whole thing just kind of evolved” from that.

The dispute’s next evolution occurred in court. Vollmer sued the Schwartzes in Montgomery County Circuit Court — not once, but twice — over arguments involving the shared driveway. She lost both.

What could possibly be driving this woman? Friend and Chevy Chase resident John Fitzgerald said that her stubborn streak has roots deep in her past. Vollmer forged her career defending the rights of those without means. And that, he said, inculcated in her a desire to protect principles until the bitter end. “Usually, we admire people like this,” he said. “But yes, this usually isn’t over a driveway.”

Into this world fraught with ego and lawsuits walked construction contractor Jose Rodriguez. The Schwartzes had charged him with the responsibility of paving a section of their property surrounding their garage, a job he said that turned out to be a “nightmare.”

“I’ve witnessed similar things to this, but not to this extent,” said Rodriguez, who recalled 10 instances in which Vollmer confronted him and his workers. “She said, ‘I’m not going to be bullied around by the rich people!’ And I was like, ‘Excuse me, you live in Chevy Chase, and you’re complaining about not being rich?’ ”

The absurdity hit its apex when, around this time, Vollmer scrawled “No justice, no peace” into unset pavement on the Schwartzes’ property, precipitating her arrest on misdemeanor charges of malicious destruction of property. The lawyer was convicted, spent a night in jail, and was sentenced to 18 months — a sentenced suspended on the condition she undergo anger management classes and cease all contact with the Schwartzes and their property.

“We have had to go to court more than 16 times because of her multiple lawsuits and her behavior,” Schwartz said. “We love our home and our neighborhood, and we can only hope that reason will prevail in the future.”

But peace, in spring 2014, was the last thing on either of their minds. More drama had ruptured a brief armistice.

Arthur Schwartz offered to pay to repair the shared driveway, which inclement weather had turned into a muddy mess. But this offer — made through his lawyers, of course; the neighbors haven’t communicated verbally in three years —was rejected. So Schwartz sued Vollmer, seeking a declaratory judgment that would accord him the right to repair the driveway.

The trial court ordered the repair to march forward and prohibited Vollmer from interfering — an order Vollmer ignored. She confronted Rodriguez when he rolled up to the homes in April, leading to another arrest. Vollmer was ultimately held in contempt of court.

These days, the retired lawyer looks upon the paved driveway from her window, plotting her next move.

This thing isn’t over, she said on a recent morning over coffee. Her eyes twinkled with what seemed to be merriment. “If you can’t take some enjoyment out of these things,” she conceded, “you’ve got to at least find it interesting.”